1. Technical Field
Various embodiments generally relate to a semiconductor device, and more particularly, to technology for improving a sensing margin of a sense amplifier.
2. Related Art
A bit line sense amplifier of a semiconductor device may be classified as having an open bit line sense amplifier structure or a folded bit line sense amplifier structure. The operation characteristics of a bit line sense amplifier are associated with a ratio of bit line capacitance Cb to cell capacitance Cs, or Cb/Cs.
Semiconductor memory devices are highly integrated. Since cell capacitance Cs is reduced, the reduction of bit line capacitance Cb becomes increasingly important.
Accordingly, a DRAM for graphics that requires high speed operation employs a method for reducing the size of a cell mat to one half (½) in order to reduce the bit line capacitance Cb to one half (½). To this end, since the number of bit line sense amplifiers and sub-word line drivers should be increased twice, cell efficiency may be reduced.
To explain further, note that a semiconductor is fabricated from a silicon wafer. In order to maximize the number of semiconductor dies acquirable from one wafer, a critical design rule is to shrink a technology or an area of a chip through a change or the like in design architecture.
In one method of reducing the area of a chip, the size of a mat including a plurality of memory cells may be increased. When the mat size of a memory is increased, the number of sense amplifiers used between mats is reduced, so that it is possible to maximize the number of dies.
However, when the mat size of the memory is increased, the number of connected memory cells per unit bit line is increased. That is, the number of memory cells arranged in a cell mat of a unit memory is increased. Consequently, the number of cells per bit line connected to each sense amplifier is increased, so that it is possible to reduce the number of sense amplifiers.
However, the length of a bit line of a sense amplifier becomes long, resulting in an increase in the capacitance of the bit line. In such a case, since a sensing margin of the sense amplifier is reduced, it serves as a factor unfavorable to a high speed operation.
Accordingly, what are needed are semiconductor devices suitable for improving sensing margins in sense amplifiers, and/or other deficiencies of the prior art.